towards the west, being much broken. The Blue flats ironstone, 160 or 170nbfeet below the New mine coal, was worked under the tunnel for nearly 100 yards beyond the end of the New mine coal, which would make the "hade" of the fault not much more than 30° from the horizon. At other places, however, between here and Wolverhampton, the fault seems from the workings to approach very nearly to a vertical. From Wolverhampton to within a mile and a half of Cannock, Permian rocks are believed to be those found below the surface on the downcast side of the fault; but at Wyrley Bank these rocks seem to be dying out, and beyond that the Brick red sandstone and conglomerate of the New red is alone seen. A split of the fault is thought to take place near the Walk Mill, one branch proceeding due north towards Stafford into the middle of the New red, while the other continues to form the boundary of the coal-field as far as Hednesford Pool, when that likewise so far dies out as to allow some of the beds of the New red sandstone to appear on the upcast side of it. The country is here so obscure that it is very difficult to say how this takes place—whether the fault becomes evanescent, or whether the beds of New red sandstone on opposite sides of it stood originally at very different levels in the formation.
The red clays of the Essington Wood brick pits are brought in apparently on this side of the coal-field, in the same way that those of Walsall Wood are brought in on the other. A split of the boundary fault as it ranges south seems to take place about Cheslyn Hey, the upper red Coal-measures making their appearance at the surface between the branch and the main boundary fault. The dip on this western side being to north-west, the black coal-bearing measures rise out to the southward towards the Old Mitre, just as they rise out towards Daw End on the eastern side of the coal-field, the downthrow of the branch fault decreasing in each case towards the south. It is possible that the branch on the western side, which we may call the Old Mitre fault, which is known to have a downthrow of 65 yards to the west thereabouts, runs on to the south till it is cut off either by the New Invention fault, or even till it reaches the extension of the Great Bentley fault.
Position and Lie of the Red rocks surrounding the coal-field.— We will now briefly recapitulate what we know of the Permian rocks surrounding the coal-field, and then describe the position of the beds of the New red sandstone around it.:
Permian.—The Permian rocks in the narrow belt which runs S.S.W. from Cheslyn Hey towards Wolverhampton are covered towards the west by beds of conglomerate belonging to the New red sandstone, occasionally seen in situ; but still farther west. Professor Ramsay informs me that brown speckled sandstone (Permian) is seen at one or two places, especially in an old quarry a little to the N.E. of Bushbury Hill, and that the way in which these rocks appear involves the necessity of their being brought to the surface by faults having upthrows to the west, as drawn in the latter editions of the map and in Mr. Hull's Section. No. 45.)
Pale wine-coloured and nearly white sandstones, often highly calcareous, were exposed in the cuttings of the railways at Wolverhampton, dipping sometimes at an angle of 5° or 6° to the west. These were also believed to be Permian sandstones. Just
